1. FIELD OF THE INVENTION
The present invention relates to electrochromic elements as well as various dimmers and display devices using the same.
2. DESCRIPTION OF THE RELATED ART
Electrochromic elements (hereafter simply referred to as EC) that reversibly vary color or extinction coefficient thereof by inducing an electrochemical reaction in the elements through external application of voltage possess many characteristics that are not found with solid light emitting diode (LED) or liquid crystal display (LCD). For these reasons, it has gone forward to put ECDs to practical use as dimmer elements or elements for display in various fields of industry including electronic industry.
As techniques relating to the present invention, there are inorganic ECs using transition metal oxides or organic EC using electroconductive organic polymer or viologen derivatives, etc.
A basic construction of the aforesaid inorganic ECs composed of transition metal oxides is a laminate comprising a pair of electrodes composed to ITO (In.sub.2 O.sub.3 containing 5 wt % of SnO.sub.2), etc. in a thin, transparent layer, having laminated therebetween a color-forming layer comprising various transition metal oxides and further thereon a dielectric layer (or a solid electrolyte) in thin layers.
These inorganic ECS enable elements possess advantages that enable elements to miniaturize, form into thin layers, render durable, stably operate over long periods of time, etc. On the other hand, however, disadvantages are pointed out that change between coloring and decoloring is poor when voltage is applied and response is also questionable.
This is because oxidatively color-forming materials suitable as opposing electrodes of reductive color-forming layers comprising WO.sub.3, etc. are not found in inorganic materials.
On the other hand, a basic construction of organic EC is a laminate comprising a pair of thin layered, transparent electrodes composed of the foregoing ITO, etc. having laminated therebetween a conductive polymer such as polyaniline, polypyrrole, polythiophene, etc. or viologen derivatives., or a cell having sealed them together with electrolytic solutions.
These organic ECs exhibit superior responsibility to inorganic ECs but the durability of the elements comes into a problem; it is pointed out that stable operation over long periods of time is still uncertain. This is because excellent reductive color-forming materials are not found in organic materials.
As above, ECs of both types involve advantages and disadvantages, respectively, and it is the actual situation that any of ECs does not satisfactorily exhibit their properties intrinsic to ECs.
In recent years, a sunroof has been extensively mounted for purposes of making the inside of a car an open atmosphere and controling lightness of the inside.
As shown in FIG. 4, sunroof 30 in the art related to the present invention comprises roof part 31 made of a steel plate and glass part 32 and is designed to control a quantity of incident light into the inside of a car by moving roof part 31 manually or by driving with a motor. Aside from this sunroof 30, there is known a sunroof of type that reduces a quantity of incident light into the inside by printing mesh patterns on the glass part.
Even in either case of manual operation or driving with a motor, however, the operation of the above-described sunroof 30 is complicated because the quantity of incident light must be controlled viewingly.
Further in the case of the mesh type sunroof, a problem encounters that the quantity of incident light cannot be increased or decreased.
Next, a room mirror of a car is equipped with an antiglare mechamism.
As shown in FIG. 7, the antiglare mechanism of room mirror 60 in the art related to the present invention utilizes a prism mirror, which comprises two mirror surfaces 61a and 61b having reflectances different from each other and designed to prevent dazzling of the driver due to reflection of a headlight coming from a car which follows in the night, by hanging the reflection angle. Further aside from the room mirror 60, there has been proposed a mirror capable of changing reflectance in the mirror surface utilizing changes in extinction of light by liquid crystals, also called liquid crystal mirror.
However, the room mirror 60 in the art relates to the present invention encounters a problem that the rear visibility is reduced upon glare shielding, although the room mirror provides a satisfactory antiglare effect.
On the other hand, in the case of the liquid crystal mirror, liquid crystals are largely dependent upon the angle of view, and therefore, a problem encounters that a satisfactory rear visibility is obtained only with difficulty.
Next, an instrument panel equipped with a tachometer, a speedometer, a hazard lamp, etc. is mounted in the front of a driver's seat of a car.
However, the instrument pannel is located considerably down to the driver's eyes in driving a car so that it is troublesome that the driver must turn his eyes down whenever he intends to confirm informations displayed thereon.